Radiation, diagnosis, and management.

The biomedical effects of ionizing and nonionizing radiations include responses that are known to have thresholds ("nonstochastic" effects) as well as responses that are presumed to have no thresholds ("stochastic" effects). The latter include mutagenic, carcinogenic, and teratogenic effects. Present radiation risk management strategies seek to protect completely against nonstochastic effects by preventing anyone from accumulating a dose of radiation in excess of the relevant threshold. Protection against stochastic effects, on the other hand, is sought by limiting the level of radiation exposure sufficiently to keep the resulting risks of such effects within acceptable bounds. For this purpose, a limit is placed on the cumulative dose that may be received by any tissue of the body.